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Wiki source code of Your First Stateful Project

Version 15.1 by Pascal Robert on 2012/08/09 05:00
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1 So far, we have seen two of the technologies, D2W and ERRest, that Project Wonder offers for viewing and managing the data. In this tutorial, we will show how to do it with the "stateful" way of doing things. Stateful have been around since the beginning of WebObjects in 1996, so it's the oldest way of presenting data and constructing pages.
2
3 Stateful means that you don't have to worry about creating sessions and keeping track of data coming from HTML input fields and controls. In fact, D2W is also stateful.
4
5 In this tutorial, we are also going to use the Ajax framework, who is stateful too. We will replicate the functionalities of the two other tutorials, but by creating pages ourselves. The application will have the following pages:
6
7 * The main page will display a list of blog entries, with a link to see the blog entry.
8 * The main page will have a link to an "admin" page that will show a login form.
9 * After login, a list of blog entries with links to edit, delete and create blog entries will be show.
10 * We need a form to edit/create blog entries.
11
12 Let's start by creating a new project in Eclipse. You need to create a **Wonder Application** project type, and name it **StatefulBlog**.
13
14 [[image:Capture d’écran 2012-08-06 à 04.56.13.png||border="1"]]
15
16 Just like the D2W tutorial, you need to link the application with the **BlogCommon**, **Ajax** and **H2PlugIn** frameworks. To do so, right-click on **StatefulBlog** and select **Build Path** > **Configure Build Path**. 
17
18 [[image:Capture d’écran 2012-07-29 à 14.25.46.png||border="1"]]
19
20 In the **Libraries** tab, click on **Add Library**. Select **WebObjects Frameworks** and click **Next**. Check **Ajax**, **BlogCommon** and **H2PlugIn** from the list and click **Finish**. The **Libraries** tab should look like this:
21
22 [[image:Capture d’écran 2012-08-06 à 05.15.32.png||border="1"]]
23
24 We are ready to code Open the **Components** folder of the project, and open **Main WO**. In the **Related** view (bottom-right), you see that all related files of the component are listed, and we need to open the Java code associated with the component. To do so, in the **Related** view, double-click on **Main.java** to open the Java class into an editor.
25
26 In **Main.java**, we need some Java code to get the list of blog entries so that we can show that list into the component. The following code will do what we need:
27
28 {{code}}
29
30 import your.app.model.BlogEntry;
31
32 import com.webobjects.appserver.WOContext;
33 import com.webobjects.eoaccess.EODatabaseDataSource;
34 import com.webobjects.eocontrol.EOEditingContext;
35
36 import er.extensions.batching.ERXBatchingDisplayGroup;
37 import er.extensions.components.ERXComponent;
38 import er.extensions.eof.ERXEC;
39
40 public class Main extends ERXComponent {
41
42 private EOEditingContext _ec;
43 private BlogEntry _blogEntryItem;
44
45 public Main(WOContext context) {
46 super(context);
47 EODatabaseDataSource dataSource = new EODatabaseDataSource(editingContext(), BlogEntry.ENTITY_NAME);
48 ERXBatchingDisplayGroup<BlogEntry> dg = new ERXBatchingDisplayGroup<BlogEntry>();
49 dg.setNumberOfObjectsPerBatch(20);
50 dg.setDataSource(dataSource);
51 dg.setObjectArray(BlogEntry.fetchAllBlogEntries(editingContext(), BlogEntry.LAST_MODIFIED.descs()));
52 }
53
54 private EOEditingContext editingContext() {
55 if (_ec == null) {
56 _ec = ERXEC.newEditingContext();
57 }
58 return _ec;
59 }
60
61 public void setBlogEntryItem(BlogEntry blogEntryItem) {
62 this._blogEntryItem = blogEntryItem;
63 }
64
65 public BlogEntry blogEntryItem() {
66 return this._blogEntryItem;
67 }
68
69 }
70
71 {{/code}}
72
73 [[ERXBatchingDisplayGroup>>http://jenkins.wocommunity.org/job/Wonder/lastSuccessfulBuild/javadoc/er/extensions/appserver/ERXDisplayGroup.html]] is a subclass of WODisplayGroup, a utility that adds multiple actions and logic to a list of objects. One of the best features of ERXBatchingDisplayGroup is that it does real batching (if the RDBMS that you use supports it), so that means that if we specify a batch of 20 objects (//dg.setNumberOfObjectsPerBatch(20)//), it will fetch only the first 20 objects from the database, and if you switch to the next batch, the display group will go to the database to get the next 20 objects. ERXBatchingDisplayGroup is useful if you known that your list will contains hundred of objects.
74
75 Let's edit the component. Open **Main.wo** and edit the content in the top panel to be:
76
77 {{code}}
78
79 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
80 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
81 <head>
82 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
83 <title>untitled</title>
84 </head>
85 <body>
86 <h1>Our super blog</h1>
87 <wo:if condition="$displayGroup.hasMultipleBatches">
88 <div>
89 <wo:link action="$displayGroup.displayPreviousBatch">Previous</wo:link>
90 | Batch
91 <wo:str value="$displayGroup.currentBatchIndex" />
92 of
93 <wo:str value="$displayGroup.batchCount" />
94 |
95 <wo:link action="$displayGroup.displayNextBatch">Next</wo:link>
96 </div>
97 </wo:if>
98 <wo:loop list="$displayGroup.displayedObjects" item="$blogEntryItem">
99 <p><wo:str value="$blogEntryItem.title" /></p>
100 <p><wo:str value="$blogEntryItem.content" escapeHTML="false" /></p>
101 <p>Created by
102 <wo:str value="$blogEntryItem.author.fullName" />
103 on
104 <wo:str value="$blogEntryItem.creationDate" />
105 </p>
106 <hr />
107 </wo:loop>
108 </body>
109 </html>
110
111 {{/code}}
112
113 The condition //displayGroup.hasMultipleBatches// checks if we have more than 20 objects. If that's true, we will show a HTML div with links to navigate between batches. After that condition, we loop over the displayedObjects (the current batch of objects) and we use WOString elements to display details about each blog entry.
114
115 You can run the application to check if everything is working. If everything is ok, terminate the app.
116
117 The next steps is to build the administration part of the application. The first thing we need to do is to add a variable and two methods in **Session.java** that will store the logged user. Open **Session.java** and add the following code:
118
119 {{code}}
120
121 private Author _loggedAuthor;
122
123 public Session() {
124 this._loggedAuthor = null;
125 }
126
127 public Author loggedAuthor() {
128 return this._loggedAuthor;
129 }
130
131 public void setAuthor(Author loggedAuthor) {
132 this._loggedAuthor = loggedAuthor;
133 }
134
135 {{/code}}
136
137 Save the file. Next: we need to add a component to present the login form to the user. Right-click on the **Components** folder in the project, and select **New** > **WOComponent**. Change the name of the component to be **AdminMainPage** and change the superclass to **er.extensions.components.ERXComponent**.
138
139 After the component have been created, open **AdminMainPage.java** and override the content of the class with the following code:
140
141 {{code}}
142
143 package your.app.components;
144
145 import your.app.Session;
146 import your.app.model.Author;
147 import your.app.model.BlogEntry;
148
149 import com.webobjects.appserver.WOActionResults;
150 import com.webobjects.appserver.WOContext;
151 import com.webobjects.eoaccess.EODatabaseDataSource;
152 import com.webobjects.eocontrol.EOEditingContext;
153
154 import er.extensions.batching.ERXBatchingDisplayGroup;
155 import er.extensions.components.ERXComponent;
156 import er.extensions.eof.ERXEC;
157
158 public class AdminMainPage extends ERXComponent {
159
160 private ERXBatchingDisplayGroup<BlogEntry> _dg;
161
162 public AdminMainPage(WOContext context) {
163 super(context);
164 EODatabaseDataSource dataSource = new EODatabaseDataSource(editingContext(), BlogEntry.ENTITY_NAME);
165 _dg = new ERXBatchingDisplayGroup<BlogEntry>();
166 _dg.setNumberOfObjectsPerBatch(20);
167 _dg.setDataSource(dataSource);
168 _dg.setObjectArray(BlogEntry.fetchBlogEntries(editingContext(), BlogEntry.AUTHOR.eq(session().loggedAuthor()), BlogEntry.LAST_MODIFIED.descs()));
169 }
170
171 public ERXBatchingDisplayGroup<BlogEntry> displayGroup() {
172 return this._dg;
173 }
174
175 private String _emailAddress;
176
177 public String emailAddress() {
178 return this._emailAddress;
179 }
180
181 public void setEmailAddress(String emailAddress) {
182 this._emailAddress = emailAddress;
183 }
184
185 private BlogEntry _blogEntryItem;
186
187 public void setBlogEntryItem(BlogEntry blogEntryItem) {
188 this._blogEntryItem = blogEntryItem;
189 }
190
191 public BlogEntry blogEntryItem() {
192 return this._blogEntryItem;
193 }
194
195 @Override
196 public Session session() {
197 return ((Session)super.session());
198 }
199
200 public boolean isLogged() {
201 return ((session()).loggedAuthor() == null) ? false: true;
202 }
203
204 private EOEditingContext _ec;
205
206 public EOEditingContext editingContext() {
207 if (_ec == null) {
208 _ec = ERXEC.newEditingContext();
209 }
210 return _ec;
211 }
212
213 private String _errorMessage = null;
214
215 public String errorMessage() {
216 return this._errorMessage;
217 }
218
219 public WOActionResults login() {
220 Author loggedAuthor = Author.validateLogin(editingContext(), _emailAddress);
221 if (loggedAuthor != null) {
222 session().setAuthor(loggedAuthor);
223 } else {
224 _errorMessage = "Invalid email address";
225 }
226 return null;
227 }
228 }
229
230 {{/code}}
231
232 You will notice that we are using a ERXBatchingDisplayGroup again. But this time, when we call dg.setObjectArray//, we set the array of objects so that only the blog entries created by the logged author are displayed.//
233
234 Open **AdminMainPage.wo** and override all the content between the <body> tag to be:
235
236 {{code}}
237
238 <wo:AjaxUpdateContainer id="main">
239 <wo:if condition="$isLogged">
240 <wo:if condition="$displayGroup.hasMultipleBatches">
241 <div>
242 <wo:link action="$displayGroup.displayPreviousBatch">Previous</wo:link>
243 | Batch
244 <wo:str value="$displayGroup.currentBatchIndex" />
245 of
246 <wo:str value="$displayGroup.batchCount" />
247 |
248 <wo:link action="$displayGroup.displayNextBatch">Next</wo:link>
249 </div>
250 </wo:if>
251 <table>
252 <tr>
253 <th><wo:WOSortOrder displayGroup="$displayGroup" key="title" /> Title</th>
254 <th>Author</th>
255 <th><wo:WOSortOrder displayGroup="$displayGroup" key="creationDate" /> Created on</th>
256 <th><wo:WOSortOrder displayGroup="$displayGroup" key="lastModified" /> Last modified</th>
257 </tr>
258 <wo:loop list="$displayGroup.displayedObjects" item="$blogEntryItem">
259 <tr>
260 <td>
261 <wo:str value="$blogEntryItem.title" />
262 </td>
263 <td> <wo:str value="$blogEntryItem.author.fullName" /> </td>
264 <td> <wo:str value="$blogEntryItem.creationDate" dateformat="%Y/%m/%d" /> </td>
265 <td> <wo:str value="$blogEntryItem.lastModified" dateformat="%Y/%m/%d" /> </td>
266 </tr>
267 </wo:loop>
268 </table>
269 </wo:if>
270 <wo:else>
271 <wo:if condition="$errorMessage">
272 <span style="text-color: red;">Error: <wo:str value="$errorMessage" /></span>
273 </wo:if>
274 <wo:form>
275 <div>
276 <label>Email address:</label>
277 <wo:textField value="$emailAddress" />
278 </div>
279 <div><wo:AjaxSubmitButton updateContainerID="main" action="$login" value="Login" /></div>
280 </wo:form>
281 </wo:else>
282 </wo:AjaxUpdateContainer>
283
284 {{/code}}
285
286 Last step: we need a link to the admin page. Open **Main.wo** and just before the </body> tag, add the following:
287
288 {{code}}
289
290 <wo:link pageName="AdminMainPage">Admin</wo:link>
291
292 {{/code}}
293
294 Save everything, run the app and try to login. If login is not successful, you will get an error message. If login is valid, you will see the blog entries that you created.
295
296 For the last part of this tutorial, we are going to add a link on each blog entry in the list that will bring us to a edit page where we can modify a blog entry. We are also going to add a link to create a new blog entry.
297
298 Create a new component, and name it **EditBlogEntry**. Open **EditBlogEntry.java** and override the code with:
299
300 {{code}}
301
302 package your.app.components;
303
304 import your.app.Session;
305 import your.app.model.Author;
306 import your.app.model.BlogEntry;
307
308 import com.webobjects.appserver.WOActionResults;
309 import com.webobjects.appserver.WOContext;
310 import com.webobjects.eocontrol.EOEditingContext;
311
312 import er.extensions.components.ERXComponent;
313 import er.extensions.eof.ERXEC;
314 import er.extensions.eof.ERXEOControlUtilities;
315
316 public class EditBlogEntry extends ERXComponent {
317
318 public EditBlogEntry(WOContext context) {
319 super(context);
320 }
321
322 private BlogEntry _blogEntry;
323
324 public BlogEntry blogEntry() {
325 return this._blogEntry;
326 }
327
328 public void setBlogEntry(BlogEntry blogEntry) {
329 if (blogEntry == null) {
330 this._blogEntry = ERXEOControlUtilities.createAndInsertObject(editingContext(), BlogEntry.class);
331 Author localUser = ERXEOControlUtilities.localInstanceOfObject(editingContext(), session().loggedAuthor());
332 this._blogEntry.setAuthorRelationship(localUser);
333 } else {
334 this._blogEntry = ERXEOControlUtilities.localInstanceOfObject(editingContext(), blogEntry);
335 }
336 }
337
338 private EOEditingContext _ec;
339
340 public EOEditingContext editingContext() {
341 if (_ec == null) {
342 _ec = ERXEC.newEditingContext();
343 }
344 return _ec;
345 }
346
347 @Override
348 public Session session() {
349 return ((Session)super.session());
350 }
351
352 public WOActionResults save() {
353 editingContext().saveChanges();
354 return pageWithName(AdminMainPage.class);
355 }
356 }
357
358 {{/code}}
359
360 Open **EditBlogEntry.wo** and between the <body> tag, add the following:
361
362 {{code}}
363
364 <wo:form>
365 <div>
366 <label>Title:</label>
367 <wo:textfield value="$blogEntry.title" />
368 </div>
369 <div>
370 <label>Content:</label>
371 <wo:text value="$blogEntry.content" rows="20" cols="80" />
372 </div>
373 <div>Author: <wo:str value="$session.loggedAuthor.fullName" /></div>
374 <div><wo:submitButton action="$save" value="Save changes" /></div>
375 </wo:form>
376
377 {{/code}}
378
379 We now have a form to edit or create a blog entry. Save the component and the Java class, and open **AdminMainPage.java** to add the following code:
380
381 {{code}}
382
383 public WOActionResults editBlogEntry() {
384 EditBlogEntry nextPage = pageWithName(EditBlogEntry.class);
385 nextPage.setBlogEntry(_blogEntryItem);
386 return nextPage;
387 }
388
389 public WOActionResults createBlogEntry() {
390 EditBlogEntry nextPage = pageWithName(EditBlogEntry.class);
391 nextPage.setBlogEntry(null);
392 return nextPage;
393 }
394
395 {{/code}}
396
397 Open **AdminMainPage.wo** and just after <wo:if condition="$isLogged">, add the following line:
398
399 {{code}}
400
401 <div><wo:link action="$createBlogEntry">Create a new blog entry</wo:link></div>
402
403 {{/code}}
404
405 Find this line:
406
407 {{code}}
408
409 <wo:str value="$blogEntryItem.title" />
410
411 {{/code}}
412
413 and replace it with:
414
415 {{code}}
416
417 <wo:link action="$editBlogEntry"><wo:str value="$blogEntryItem.title" /></wo:link>
418
419 {{/code}}
420
421 Save everything, run the app, click on the "admin" link, login and check if you can create or edit a blog entry. Everything should be working, and just created your first stateful Project Wonder application